Draft regulator



NOV- 2, 1948- J. w. MILLER ET AL I DRAFT REGULATOR Filed July 2', 1945 INVENTOR.

JOHN w. MILLER BY BASIL 0. H66

ATTORNEY Patented Nov. '2, 1948 UNITED "STATES PATENT orncs assignors to Motor Wheel (lorporationpLansing, Mich, a corporation of Michigan Application July 2, 1945,seria1 Nd. 602,882

t l v This invention relates to improvements in draft regulators for combustion apparatus. v

The principal object of the present invention is to provide a draft regulator of especiallysimple and economical construction.

Another object is to provide a draft regulator, the principal parts of which can be pressed from sheet metal.

Still another object is to provide a draft regu later in which the frame for supporting the damper blade can be pressed from a single piece of sheet metal. v

A further object is to provide a draft regulator having novel means for mounting an adjustable weight.

These objects will appear more fully as the de-f scription of the invention proceeds.

In the drawings: j

Figure 1 is a front elevational view ofa draft regulator embodying the invention;

Figure 2 is a cross-sectional view taken on substantially the line 2-2 of Figure 1;

Figure 3 is an enlarged fragmentary front e1evational view of a portion of the frame shown in Figure l; r

Figure 4 is a fragmentary side elevational View of the structure shown in'Figure 3; and

Figure 5 is a fragmentarycross-sectional View taken on substantially the line 5'5 of Figure 3.

The draft regulator is of the type adapted to be mounted on the flue outlet or chimney of a conventional heating device such as an oil burning space heater or furnace, not shown. A collar I is adapted to be attached to the flue outlet at one end (not shown), and carries the draft regulator at its other, and open, end.

The draft regulator comprises a frame H and a damper blade I2 pivotally mounted in a vertical position on a horizontal axis in the frame H. The damper blade carries a balance weight as sembly l3 for regulating the draft. Theconstruction and operation of these parts will more fully appear presently. t

The frame II is an annular ring of generallyZ shaped configuration in cross section (see Figure 2) pressed from a single sheet of metal, It has a cylindrical portion M which telescopes within the open end of the collar l0. and a radially outward- 1y extending flange l which abuts the free end of the collar. At the inner end of the cylindrical portion i4 is a substantially plane radial portion or flange It provided with a relatively large opening therein to receive the damper blade l2. For the greater portion of its circumference the inner edge of the flange I6 is circular. However, at

opposite sides of the ring wardly and rearwardly above the center thereof the inner edge of the flange is straight and is provided with flat axially extending shoulders ll.

A pair of axially inwardly extending shallow depressions l8 ;are pressed in the flange 16 ad- Jacent and radially outwardly of the shoulders ll forla purpose which will appear presently. The

shoulders ll are extended axially outwardly a I substantial distance and terminate at their axiala ly outer extremities in radially extending stop lugs 19. Generally *oval apertureslllare formed in the shoulders l'lv with their longer axes in a horizontal position. The centers of the apertures Zil arelocated in the plane of the flange l6.

Somewhat below the lugs H] are two more stop lugs 2!. These lugs are offset axially outwardly from the flange It: a distance approximately equal to the thickness of the damper blade [2. The lugs 2i extend radially inwardly from the flange IS.

The damper blade is a single sheet metal stamping having a shape the same as that of the opening in the frame I l but very slightly smaller thanthe opening. At opposite sides of the blade the metal thereof is slit at 22 and ispressed forr to provide pockets to receive pivot shafts 23. The pivot axis is located above the center of the bladeand in line with the 5 apertures 20in the frame when the blade is in the rame.

Somewhat above the center of the blade the meta-1 thereof is pressed axially outwardly to provide a circular recess 24. The center of the recess is located above the pivotaxis, andan openingis punched in the center of thelrecess.

orally 2, support 25, a shaft 25, a weight 21' and a knob 28. Preferably the support is extruded from relatively soft metal. It has a hub 29 and a flange 3!]. The hub has a holetherethrough to receive the shaft 26 and the wall of the hole is provided with a helical groove 3|. The flange 30 may be riveted or otherwise secured to-the outer surface ofthe] recess 24 withthe hub extending i through the opening-therein.

. v The shaft 25 is rotatablymountedin the hole in the hub 29; Intermediate the ends of the shaft is a cylindrical recess which receives a coil spring 32 and a hemispherical headed plunger 33. The latter fits in the-groove 3| and is held therein by spring 32. A stop pin 34 is threaded into the shaft 26 in spaced relation to theplunger 33. t

The weight 21 is provided with a recess 35 to receive the hub 29 when the weight is adjusted to a position next to the blade l2. The weight i is secured on the axially inner end of shaft 26 a cane.

The balance weight assembly l3 comprises genby peening over the end of the shaft. The knob 28 is attached to the outer end of the shaft. Preferably the knob is shaped like a pointer, or carries a pointer which cooperates with dial figures on the flange 30 to indicate the setting of the weight.

Since the damper blade is pivoted above center, the air pressure on the lower portion of the blade is greater than that on the upperportion so that the lower portion tends to swing inward and the upper portion outward when there is any draft in the flue outlet, to admit air to the flue. The admission of air to the flue tends to'reduce the draft on the burner. Any tendency .for .the draft to fluctuate is compensated for by "the damper blade swinging to admit'more orless air to the flue and thereby maintain a constant draft. The damper swings easily without appreciable friction as the pivot shafts 23 roll the .bottom edges of the oval apertures 20.

The draft may be regulated by rotating the knob 28. That causes the weight 21 to move toward or away from the plane of the blade. When the weight is closest to the blade the latter "is statically balanced and offers no resistance to swinging. Wheretheweight is moved awayfromthe blade it counteracts the tendency of the -'-air pressure to swing the blade, and'in its position *farthest from the blade the weight offers its greatest resistance to swinging movement of the blade, thus maintaining the greatest draft ontheburner.

The stops l9 limit the opening movement of the damper blade, as the latter strikes the upper edges of those stops whenthe blade has turned through a little less than 90 from its vertical position. The stops 2! prevent'the'damper from swinging'in jtheopp'osite direction from the vertical, in case a sudden back draft'should tend to create sucha movement of the blade.

Fromthe foregoing it will be apparent that the, present inventionprovides an extremelysimple and economical 'draftregulator, as the blade and frame can be formed as, one piece sheet metal stampings. Also, the balance weight assembly can-be cheaply and easily fabricated and assembled.

Thescopeof the'invention is indicated in the appended claims.

We claim:

1. A draft regulator 'comprisinga one piece frameprovidedwitha central opening, a damper blade substantially filling said opening, vmeans pivotally connecting said damper blade to said frame onan axis offsetradially from thecenter of the blade and dividing, the latter into a, minor portion anda major portion, a balance weight assembly mounted in the minor, portion in spaced relation to the pivot axis, said balance weight assembly comprising ,a;hub having a bearing therein and a helical. groove in the .wall. of said bearing, ashaft rotatably mounted in ,saidibearing, saidshafthavingra-spring pressed pin therein witht-he free-end'of' the, latter seated in said groove, and a weightp'fixedly mounted'on the axially inner 'end' ofrsaid :shaft.

2. A draft regulator comprising a one piece annular frame having a circumferentially continuous substantially plane portion provided with a central opening, said plane portion having a pair of axially inwardly extending depressions therein offset radially from the center of said frame, the radially inner sides of said depressions being defined by axially .outwardly.. extendingshoulders,

asaid :shoulfders having ialign'ed openings therein,

a damper blade substantially filling said opening,

pivot shaft means attached to said damper blade and received in the openings in said shoulders forxpivotally mounting said damper blade in said frame, and stop means integral with said frame -.for..limiting,the pivotal movement of said blade in both directions from said plane portion.

- vided with "a central opening, a damper blade fixedly mounted on one 3. A draft regulator comprising a frame prosubstantially filling said opening, means pivotally connecting said damper blade to said frame on an axis substantially .in theplane of the blade, a balance weight assembly connected to the blade inspacedrelation to thejpivot axis of the latter, said'balance weight assembly comprising a hub member havinga bearing therein, alshaft member. rotatablymountedin said bearing, one of said members having a substantially helical gui'cleway therein, the other member .havinga spring,pressedsfollower, one end of said follower being seatediin said lastnamed member and the other end-seated in said guideway, anda weight end of said -shaft.mem-

ber. I

. 4.. A draft regulator comprising a frame provided with a central opening, a damper blade substantially filling saidopening, means. pivotally connecting saiddamperblade to said frame on an axis substantially in the plane-of the blade and offset .radiallyfrom the center "of the latter whereby to divide ;the blade vinto a minor portion anda .major .portion, a balance weight assembly mounted in themino'r portion in spaced relation to thevaxis of the blade, said balance weight assemblyeomprising a ing a bearing therein, a shaft member rotatably mountedlinssaidbearing, one-of said members having a substantially :helical guideway therein, the.QthenmemberhaVing-a spring .pressed follower, -.0ne-end of said .follower being seated in saidlast.namedlmember-and the other end seated in saidguideway and aweight fixedly mount ed on one endofsaid shaft member.

JOHN W. MILLER; BASIL D. ,FIGG.

REFERENCES 'CITED .The following references areof record in the} "Field A'Dec- ,15, ,.1'9.39 Field Oct. .'6, 1942 Number 2,182,625 2,297,757

hub, memberhav- 7 

